Pain-alleviating apparatus for dental drilling

ABSTRACT

Apparatus is described for reducing pain during dental drilling by introducing electric current into the tooth via the drilling bur. The apparatus takes advantage of the high intensity lamp present to illuminate the drilling area by providing on the handpiece a photo-responsive device for generating or controlling the voltage or current applied to the bur. Various modifications are described for different kinds of handpieces.

United States Patent Ellman July 17, 1973 [54] PAIN-ALLEVIATING APPARATUS FOR 3,083,463 4/1963 Brooks et a1 32/48 N L L G 3,543,405 l2/l970 Banhart Primary Examiner-Robert Peshock Attorney-Jack Oisher [5 7] ABSTRACT Apparatus is described for reducing pain during dental drilling by introducing electric current into the tooth via the drilling bur. The apparatus takes advantage of the high intensity lamp present to illuminate the drilling area by providing on the handpiece a photo-responsive device for generating or controlling the voltage or current applied to the bur. Various modifications are described for different kinds of handpieces.

9 Claims, 5 Drawing Figures PAIN-ALLEVIATING APPARATUS FOR DENTAL DRILLING This invention'relates to dental apparatus for alleviating pain during a dental drilling operation.

Prior art has described various methods and apparatus for alleviating pain for certain people during a dental drilling operation by passing electric current through the drilling bur directly into the tooth being excavated. Previous devices show an ordinary electric battery connected between the bur activating shaft and an electrode to be applied to the head or body of the patent. The connection to the rotating activating shaft is made by a sliding contact. The handpiece through which the rotating shaft extends is also described as being insulated. In US. PatfNo. 535,905, Horton et al. describes an improved apparatus employing a resistance box connected between the battery and the bur in order to vary the quantity of current in the circuit, and also describes the use of a head band for establishing a better electrode contact to the patients face on the side where the tooth to be drilled is located.Both of these require an external battery and'complicated connections to the handpiece, which is disadvantageo'us. If the battery is of the dry-cell type, frequent replacement may be necessary; if a house current operated power supply is used, the required apparatus is cumbersome and expensive.

There is also described an improved apparatus which eliminates the battery. This is accomplished by replacing the normal drilling bur with a special but containing an electric coil of wound wire of which one end'is connected to the bur shank and whose other end, which is bare, extends throughthe bur to project below its bottom surface. When such a bur is rotated inn the presence of an externally supplied magnetic field, an electromotive force is presumably generated in the coil between the wire ends causing a current to flow through the tooth between the but and the bare wire end which must be maintained in electrical contact with the tooth. This introduces certain disadvantages. The provision of external magnets to supply the magnetic field as described in this patent is cumbersome and may interfere with the drilling operation on the patient. The special bur containing an embedded coil will be expensive to manufacture and will be expensive toreplace after it wears out. High speed rotation of the bur could perhaps spoil the contact of the protruding wire end with the tooth. To vary the tooth current as indicated by the patients response may require variation of the magnetic field intensityor variation of the number of coil'turns. This requires either the use of electromagnets with current varying means, whichis cumbersome, or a stock of burs with different sized coils to be employed on a trial and error basis until the most favorable combination is attained, which will be tim consuming as well as expensive. A recently improved version'provides several coils within the handpiece head and a permanent magnet on the rotor. One coilend is connected to the bur, and the other coil end to a wire to be connected to the patient. This handpiece construction is complicated and expensive, and moreover variation or control of the electrical impulse is not possible.

My present invention is an improvement of the foregoing apparatus and isbased on the concept of using light to develop or control the voltage applied to the tooth via the bur. In a preferred embodiment in accordance with my invention, I provide a photovoltaic device such as a solar cell in the handpiece and connect one of the two terminals of the photovoltaic device to the bur and the other to an electrode to be connected to the patient. My invention takes advantage of the fact that a strong source of artificial light is located close to the patient and directed into the patients open mouth toilluminate the tooth being excavated, and thus the handpiece containing the bur is located directly in the path of the light duringthe drilling operation. Thus, a photovoltaic device mounted'on the handpiece will develop a voltage and sufficient current to alleviate at least in part for certain patients the usual pain that accompanies dental drilling.

A further feature is to use a photoconductive device in series'with a voltage source to control the current through the tooth; Again, mounting of the photoconductivedevice on the handpiece ensures that while in use the photoconductive device is constantly exposed to a strong source of light.

Among the advantages obtainable with my invention are safety, simplicity, low-cost construction, and ready control. From the safety standpoint, an overvoltage or overcurrent' is impossible if beyond the inherent capabilities of the photovoltaic device. A simple and lowcost construction is possible because no special burs or complicated circuitry is required. All that is needed is to mount'a suitably chosendevice on the topside of the handpiece and make the appropriate connections.

Control is simplified by providing a manual shutter over the photovoltaic device or the series connected photoconductive cell.

Other advantages of the invention willbecome apparent from the following detailed description of several'embodiments thereof when taken in conjunction with'the accompanying drawings wherein:

FIG. 1 is a schematic view of one embodiment using a photovoltaic device in accordance with my invention for use with aconnected bur-head handpiece;

FIG. 2 is a side view showing a modification adapted to be added'to a standard handpiece;

FIG. 3 showsanother variation for a-connected burhead handpiece;

FIG; 4 shows still-a further modification for an insulated bur-head handpiece;

FIG. 5 is a schematic view of an'embodiment in accordance with'my inventionusing a photoconductive cell. 1

' As is described in the above-mentioned prior patents, certain patients find'that the painnormally experienced duringa dentaldrilling operation canbe alleviated at least in part by introducingelectric current into the toothviathe drilling bur. The current required is very small, of the order of'several or tens of microamps. To provide this current only from about one to several tenths of a volt isneeded to be applied between the, bur and the-patient; In contrast to the'manner described in the artfor generating or controlling the voltage applied to the bur, I use the effect of incident'light or equivalent radiation on a photovoltaic or photoconductive device. As is well known, the usual dental unit includes a high-intensity lamp which is adjustable in position to illuminate the patientsmouth while the dentist workstherein. My invention'takes advantage of the presence of thishigh intensity light source-to generate or control the voltage or current applied tothe bur.

FIG. 1 illustrates schematically the outline of a wellknown contraangle air handpiece of the high-speed variety. The interior details are not important to my invention except that, in its most common form, all of the handpiece is made up of metal, electrically conductive parts and thus the bur, when inserted in the chuck, becomes electrically connected to the metal head, the metal handle, and the connecting shank (hereinafter referred to as the connected bur-head type), whereas in the less common variety of the so-called silent type handpiece, due to the use of noise-dampening inserts in the bearings, which inserts are of an insulating nature, the bur when mounted is not electrically connected to the metal head, the metal handle, or the connecting shank (hereinafter referred to as the insulated bur-head type), and thus the electrical connections of my photo responsive device will be different for the two different types of handpieces having electrically connected or insulated burs. Such air handpieces are well known and are available commercially from many suppliers to the dental industry.

The FIG. 1 embodiment is for the connected burhead type. The handpiece designated comprises a head portion 11, a handle portion 12 and a connecting shank portion 13. A chuck is provided in the head 11 for receiving the usual cutting bur 9. In accordance with my invention, 1 incorporate in or on the connecting shank 13 a photovoltaic device 15. The latter can be of any well known type commercially available in many sizes and shapes and of different materials and capable of generating a voltage in response to incident light, shown schematically by the arrows 16. The material of the device determines the voltage generated, and the size determines the current capability. To increase the voltage several units can be connected in series, and to increase the current several units can be connected in parallel. Any of the well-known semiconductors, such as selenium, germanium, or silicon, can be used. A suitable device is the so-called solar cell; see for example, PIEEE, May I963, pps. 667-674; RCA Review, Sept. 1959, pps. 373-397; J. Brit. IRE, Oct. 1958, pps. 583-594. Such devices have two output terminals across which the developed voltage is available. In a popular construction, the semiconductor is mounted on a metallic base which constitutes one terminal, and an electrical lead comes off the top which represents the second terminal. In the FIG. 1 embodiment, such a device is permanently mounted on the handpiece 10 as by soldering the metallic base 17 to the handpiece or mounting onto a conductive enclosure. A conductive adhesive can also be used. The second terminal, designated 18, is provided with a connecting wire 19 which terminates in a spring clip 20. The bur 9 will be at the potential of the first terminal 17. All that now has to be done is to connect the wire 19 to the patient. A preferred way is to attach the clip 20 to the usual saliva ejector 21, and insert the latter in the mouth of the patient. This will establish a good electrical connection to the patients jaw allowing current to flow into the tooth via the bur depending upon the illumination intensity on the device 15. Adjusting the lamp intensity will give some control of the current through the tooth.

FIG. 2 illustrates a modification wherein the solar cell is mounted on a metal spring clip 23 which in turn can be clipped over a standard handpiece of the connected bur-head type again causing the bur to assume the potential of the first terminal 17 and the electrical wire 19 as before can be coupled to the patient. Thus my invention can be sold as an accessory for use with the dentist's present equipment.

FIG. 2 illustrates another feature wherein the current can be controlled by providing means in the device housing to vary the light intensity. This is readily accomplished by a simple manual shutter or diaphragm 25 for controlling a light opening 26 into the solar cell 15. The position of the shutter 25 can be adjusted by the dentists finger.

Electrical contact to the patient can also be effected through the dentist. A suitable modification is illustrated in FIG. 3, again for a connected bur-head handpiece. In this case, the handle portion is provided with an insulating sleeve 27, and the wire connection 19 from the second device terminal is connected to a metal band 28 bonded to the insulating sleeve and insulated from the metal handle 12. If now the dentist touches his finger, designated 29, to the band 28, and with his other hand touches the face or jaw of the patient, or a saliva ejector in the patients mouth, the electrical circuit can be completed via the dentist.

FIG. 4 illustrates a suitable construction for a handpiece 31 of the insulated bur-head type. In this case, the solar cell base 17 is connected to the handpiece 3], and the second terminal 18 is connected by a wire 32 to the insulated bur top thorugh a hole in the handpiece top or as shown, may be mounted so as to contact the bur side.

The circuit is completed through the dentist holding the handpiece when he touches the patients face, such as his lip, with his free hand.

In the above embodiments, the voltage was generated by light incident on a photovoltaic device. In the embodiment now to be described, the voltage is provided by a dry cell battery and controlled by light incident on a photoconductive cell, which is illustrated in FIG. 5. The handpiece is designated 35 and has mounted on it an insulated holder 36 for a battery 37. One terminal of the battery 37 is connected to a wire 38 which terminates in a spring clip 39, similar to that of FIG. 1, which is contacted to the patient. The other battery terminal is connected to a terminal 40 of a photoconductive cell 41 whose other base terminal 42 is secured to the metal of a connected bur-head handpiece 35. The intensity of light incident on the photoconductive cell 41 changes its resistance and therefore controls the voltage and current available at the patients tooth. The shutter illustrated in FIG. 2 or an equivalent can be used to control the incident light. Any known photoconductive cell can be used, such as a cadmium sulfideor cadmiumsulfo-selenide type. The battery 37 can also be substituted for by a photovoltaic device so that both the generated voltage and current and their control is effected by incident radiation.

Should it be found that moisture from the patient deleteriously affects the performance of the photodevices described, they can be encapsulated in known manner in a transparent waterproofing envelope, such as any of the well known clear plastic resins.

In the above embodiments, a D.C. voltage is generated and applied to the patient via the bur. It will be appreciated that AC. voltages can also be used if desired. This is readily accomplished by connecting a small transistor oscillator in series with a lead from the D.C. voltage source. Such transistor oscillators which when activated by a D.C. voltage will oscillate and generate an AC. voltage at any chosen frequency, in the audio, supersonic, or higher frequency ranges, are well known in the electronic art and readily available commercially, and thus need not be described further here. This embodiment is illustrated schematically in FIG. 2 which shows an oscillator 45 connected in series with the lead 19. The output from the oscillator 19 is coupled to the patient as'hereinabove described.

There has thus been described improved apparatus for introducing current into the tooth of a patient via the cutting drill. As will be evident, the apparatus is simple, inexpensive to construct, and takes up little additional space. Control of the current or voltage is readily effected in a very simple manner. The apparatus is inherently safe since a photovoltaic device can not generate an overvoltage or overcurrent. For different patients, different photovoltaic devices may be employed to provide different voltages and/or currents. This is especially useful for the accessory version illustrated in FIG. 2. To facilitate this purpose, the photovoltaic devices can be snapped into or out of a spring clip holder on the clip support 23. As will also be evident, the invention can also be applied to other than air-driven handpieces, such as the older mechanical types.

While the principles of the invention have now been made clear in several illustrative embodiments, there will be immediately obvious to those skilled in the art many modifications in structure, arrangement, proportions, the elements, materials, and components, used in the practice of the invention, and otherwise, which are particularly adapted for specific environments and operating requirements, without departing from those principles. The appended claims are therefore intended to cover and embrace any such modifications, within the limits only of the true spirit and scope of the invention.

What is claimed is:

1. Dental apparatus for alleviating pain for certain patients during a tooth drilling operation comprising a handpiece, a bur to be received by the handpiece and rotatable upon actuation of the handpiece, a photovoltaic device having output terminals mounted on the handpiece, means for connecting one of the output terminals to the bur, and means for coupling the other of the output terminals to the patient, whereby upon illumination of the photovoltaic device, a photovoltage is developed which can be applied via the bur to the tooth of the patient to be drilled.

2. Apparatus as set forth in claim 1 wherein the bur is electrically connected to the handpiece, said one output terminal is electrically connected to the handpiece, and the other output terminal is electrically insulated from the handpiece.

3. Apparatus as set forth in claim 1 wherein the bur is electrically insulated from the handpiece, means are provided connecting said one output terminal to the bur, and the other output terminal is electrically connected to the handpiece.

4. Apparatus as set forth in claim 1 and further including means for controlling the intensity of the light incident on the photovoltaic device.

5. Apparatus as set forth in claim 1 and further including a photoconductive cell mounted on the handpiece and connected in series with the photovoltaic device, and means for controlling the light intensity incident on the photoconductive cell.

6. Apparatus as set forth in claim 2 wherein an insulating sleeve is mounted on the handpiece and a metal contact on the insulating sleeve, said metal contact being connected to the said other output terminal, the circuit being completed via the dentist.

7. Apparatus as set forth in claim 1 wherein said photovoltaic device is mounted on a clip for clipping onto the handpiece.

8. Apparatus for alleviating pain for certain patients during a tooth drilling operation comprising a handpiece, a bur to be received by the handpiece and rotatable upon actuation of the handpiece, a source of voltage having output terminals, a photoconductive cell mounted on the handpiece, means for connecting one terminal of the voltage source to one of the bur and the patient, and means for connecting the photoconductive cell in series with the other terminal of the voltage source and the other of the bur and patient, whereby the magnitude of the voltage applied via the bur to the patients tooth depends upon the intensity of the light incident on the photoconductive cell.

9. Apparatus as set forth in claim- 8 and further including means for controlling the light intensity incident on the photoconductive cell. 

1. Dental apparatus for alleviating pain for certain patients during a tooth drilling operation comprising a handpiece, a bur to be received by the handpiece and rotatable upon actuation of the handpiece, a photovoltaic device having output terminals mounted on the handpiece, means for connecting one of the output terminals to the bur, and means for coupling the other of the output terminals to the patient, whereby upon illumination of the photovoltaic device, a photovoltage is developed which can be applied via the bur to the tooth of the patient to be drilled.
 2. Apparatus as set forth in claim 1 wherein the bur is electrically connected to the handpiece, said one output terminal is electrically connected to the handpiece, and the other output terminal is electrically insulated from the handpiece.
 3. Apparatus as set forth in claim 1 wherein the bur is electrically insulated from the handpiece, means are provided connecting said one output terminal to the bur, and the other output terminal is electrically connected to the handpiece.
 4. Apparatus as set forth in claim 1 and further including means for controlling the intensity of the light incident on the photovoltaic device.
 5. Apparatus as set forth in claim 1 and further including a photoconductive cell mounted on the handpiece and connected in series with the photovoltaic device, and means for controlling the light intensity incident on the photoconductive cell.
 6. Apparatus as set forth in claim 2 wherein an insulating sleeve is mounted on the handpiece and a metal contact on the insulating sleeve, said metal contact being connected to the said other output terminal, the circuit being completed via the dentist.
 7. Apparatus as set forth in claim 1 wherein said photovoltaic device is mounted on a clip for clipping onto the handpiece.
 8. Apparatus for alleviating pain for certain patients during a tooth drilling operation comprising a handpiece, a bur to be received by the handpiece and rotatable upon actuation of the handpiece, a source of voltage having output terminals, a photoconductive cell mounted on the handpiece, means for connecting one terminal of the voltage source to one of the bur and the patient, and means for connecting the photoconductive cell in series with the other terminal of the voltage source and the other of the bur and patient, whereby the magnitude of the voltage applied via the bur to the patient''s tooth depends upon the intensity of the light incident on the photoconductive cell.
 9. Apparatus as set forth in claim 8 and further including means for controlling the light intensity incident on the photoconductive cell. 